Overview:
This 1914 manual by Harold P. Manly, “Oxy-Acetylene Welding and Cutting,” provides a comprehensive guide to the process, delving into the materials, instruments, and practices involved. The book covers not just oxy-acetylene welding and cutting, but also related methods like electric, forge, and thermit welding, as well as soldering and brazing. It emphasizes the importance of proper preparation, including preheating, cleaning, and beveling the surfaces to be joined. It also details the criticality of using the correct flame and welding rod for different metals. The manual outlines safety precautions for handling acetylene and oxygen, and includes useful tables with information on metal properties, temperature scales, and conductivity.
The book highlights the burgeoning importance of oxy-acetylene welding, stating it is the most universally adaptable and widely used welding process. It emphasizes that success hinges on the operator’s knowledge and preparation, and warns against unskilled individuals using the process due to potential dangers.
Key Findings:
- Proper preparation is crucial for successful welding: Preheating, cleaning, and beveling the surfaces to be joined significantly impact the strength and quality of the weld.
- Different metals require different approaches: The correct flame, welding rod, and flux must be used for each metal type to achieve optimal results.
- Understanding the properties of metals is essential: Knowledge of melting points, expansion and contraction rates, and heat conductivity allows for better control and avoids potential problems.
- Oxy-acetylene welding is a safe process when properly executed: The manual emphasizes the importance of adhering to safety regulations and using proper equipment and practices.
Learning:
- The oxy-acetylene process: This process involves using a torch to create a high-heat flame by combining oxygen and acetylene gases. The heat is localized, allowing for precise welding and cutting.
- Understanding welding materials: The manual explains the characteristics and uses of oxygen, acetylene, welding rods, and fluxes. It also discusses the safety precautions required for handling these materials.
- Mastering torch practice: The book covers the importance of a neutral flame, torch adjustment, and selecting the right nozzle size for the work.
- Welding different metals: The manual provides detailed guidance on welding cast iron, malleable iron, steel, aluminum, copper, brass, and bronze, outlining the unique challenges and solutions for each.
- Alternative welding methods: The book provides an overview of electric welding, including resistance and arc welding, as well as forge and thermit welding.
Historical Context:
- The manual was published in 1914, a time of rapid industrialization: The growth of the automotive and manufacturing industries was driving the need for new and efficient methods of metalworking, leading to the widespread adoption of oxy-acetylene welding.
- The discovery of acetylene was relatively recent: The book highlights the importance of Thomas L. Willson’s accidental discovery of acetylene gas in 1892, which propelled the development of this process.
- The use of oxygen in industry was expanding: The liquid air process for separating oxygen from air was becoming increasingly prevalent, providing a readily available source for welding and other industrial applications.
Facts:
- Oxygen is 16 times heavier than hydrogen by volume. (Explained by the chemical nature of the elements)
- Acetylene is the most powerful fuel gas because it has the highest percentage of carbon. (Carbon is the primary element in most fuels)
- Acetylene gas mixed with air explodes. (All flammable gases form explosive mixtures with air)
- Acetylene is soluble in acetone. (Acetone’s properties allow it to absorb large volumes of acetylene)
- One pound of pure carbide yields 5.5 cubic feet of acetylene. (This is the theoretical yield based on chemical reaction)
- The temperature of an oxy-acetylene flame is 6,300 degrees Fahrenheit. (This is the highest achievable flame temperature from a fuel gas)
- The oxy-hydrogen flame is less powerful than the oxy-acetylene flame. (Hydrogen has a lower heating power than acetylene)
- Wrought iron is nearly pure iron, while cast iron contains carbon, silicon, and impurities. (These differences in composition lead to different properties)
- Steel contains carbon in a smaller proportion than cast iron. (The amount of carbon determines the steel’s hardness and other qualities)
- Aluminum is about one-third the weight of iron. (This makes aluminum desirable for lightweight applications)
- Copper is the best commercial electrical conductor, surpassed only by silver. (Copper’s high conductivity makes it ideal for electrical applications)
- Lead is the softest and weakest of all commercial metals. (Lead’s malleability makes it useful for pipes and roofing)
- Zinc is brittle at room temperature but becomes malleable when heated. (Zinc is used for galvanizing and in alloys)
- Tin is used for protective platings and in alloys. (Tin’s resistance to corrosion makes it a good coating)
- Nickel is a magnetic metal and is used in alloys. (Nickel increases strength, toughness, and resistance to corrosion in alloys)
- Cast iron melts at approximately 2,400 degrees Fahrenheit. (Cast iron’s melting point makes it suitable for various casting processes)
- Steel’s tensile strength varies from 50,000 to 300,000 pounds per square inch, depending on composition and processing. (Tensile strength is a measure of how much force a material can withstand before breaking)
- Aluminum bronze is strong and ductile, making it suitable for parts requiring both qualities. (Aluminum bronze’s unique combination of properties makes it useful for specific applications)
- Magnalium is an alloy of aluminum and magnesium, lighter than aluminum and strong enough for high-speed engines. (Magnalium’s properties make it suitable for demanding applications requiring lightweight materials)
- The process of case hardening adds carbon to the surface of steel, creating a hard and wear-resistant skin. (Case hardening improves the surface properties of steel while maintaining a tough core)
Statistics:
- 21% of air is oxygen by volume. (Oxygen is the key component of air that supports combustion)
- One cubic foot of acetylene gas weighs 0.0735 pounds. (This is important for calculating gas consumption)
- A pound of carbide yields approximately 4.5-5 cubic feet of acetylene. (This is the practical yield based on commercially available carbide)
- A 100-cubic-foot oxygen cylinder weighs about 9 pounds more when full than empty. (This is important for handling and transporting cylinders)
- An oxy-acetylene welding flame reaches a temperature of 6,300 degrees Fahrenheit. (This is the highest achievable flame temperature from a fuel gas)
- The oxy-hydrogen flame reaches a temperature of 4,500 degrees Fahrenheit. (This is significantly lower than the oxy-acetylene flame)
- A gallon of water must be provided for each pound of carbide in a generator. (This is a fundamental rule for safe and efficient acetylene generation)
- Acetylene gas dissolves in acetone at a rate of 24 times its own volume at atmospheric pressure. (Acetone’s ability to absorb large volumes of acetylene is key for its safe storage)
- A typical acetylene generator produces gas at a rate of 1 cubic foot per hour for each pound of carbide. (This is a general rule for calculating generator capacity)
- The oxygen pressure for welding ranges from 2 to 20 pounds, depending on the nozzle size. (Oxygen pressure is adjusted for different thicknesses of metal)
- The acetylene pressure for welding should never exceed 10 pounds. (Higher pressures can be dangerous)
- A cutting torch uses oxygen at a pressure of 10 to 100 pounds per square inch. (High oxygen pressure is essential for effectively cutting steel)
- Steel can be cut with an oxy-acetylene torch at a rate of 3 inches to 2 feet per minute. (The cutting speed depends on the thickness of the steel)
- One-tenth percent of carbon in steel gives a tensile strength of 50,000 to 65,000 pounds per square inch. (The tensile strength increases with the amount of carbon)
- Aluminum melts at approximately 1,175 degrees Fahrenheit. (This low melting point makes aluminum challenging to weld)
- Copper melts at approximately 1,950 degrees Fahrenheit. (This is significantly higher than aluminum’s melting point)
- The conductivity of aluminum is approximately 63% that of silver. (Aluminum’s high conductivity requires careful heat management during welding)
- The conductivity of copper is approximately 99% that of silver. (Copper’s high conductivity makes it a good conductor for electricity and heat)
- The weight of lead is 0.410 pounds per cubic inch. (Lead’s density is relevant for various applications, such as pipes and weights)
- Steel expands by approximately 0.083 inches per foot when heated 1,000 degrees Fahrenheit. (This expansion is important for preheating and preventing cracking during welding)
Terms:
- Autogenous welding: A welding process that involves melting the edges of the materials to be joined without the use of hammering or compression.
- Polymerization: The process of converting acetylene gas into oily matters under high temperatures, causing problems with welding torches.
- Flux: A chemical powder used in welding to clean the weld, remove impurities, and protect the molten metal.
- Spelter: A brass alloy used in brazing to join metal parts.
- Thermit: A mixture of finely powdered aluminum and iron oxide, which produces a superheated steel when ignited.
- Tensile strength: A measure of a material’s resistance to breaking under tension.
- Heat conductivity: The rate at which heat flows through a material.
- Electrolysis: The process of separating water into hydrogen and oxygen by passing an electric current through it.
- Voltage: The electrical pressure or force in a circuit.
- Amperage: The rate at which electrical current flows in a circuit.
- Alternating current (AC): Electrical current that periodically reverses its direction of flow.
- Direct current (DC): Electrical current that flows in one direction only.
- Short circuit: An unintended path for electrical current to flow, often causing a fault or damage.
- Ground: An unintended connection between an electrical circuit and the earth or a conductive object.
- Back flash: The ignition of flammable gas inside a welding torch, typically caused by a faulty nozzle or improper gas mixture.
Examples:
- Preheating a cast iron crack: The manual describes preheating a cast iron part in a charcoal-filled oven built with fire bricks to prevent cracking during welding.
- Welding a cracked fly wheel spoke: To prevent stress-induced breakage, a cut is made at the rim of the fly wheel, allowing free movement during the welding process.
- Bending a pipe without kinking: The manual describes bending a pipe at a red heat, while holding it in a vise, to avoid kinking.
- Upsetting a bar in a forge: The manual explains how to upset a short piece of iron by placing it on end on the anvil and hammering down on it to make it shorter and thicker.
- Soldering a hole in a metal sheet: The process involves cleaning the surface around the hole, applying flux, melting solder on a soldering iron, and working the solder around the hole until it is closed.
- Brazing two pieces of brass together: The manual outlines the process of heating the brass pieces to the melting point of the spelter, applying flux, and then melting the spelter into the joint to form a bond.
- Thermit welding a broken gear: The process involves preheating the gear, filling the gap with wax, packing the mold with a fire clay mixture, melting the thermit, and pouring the molten steel into the mold to join the gear.
- Removing carbon deposits from an engine cylinder: The manual details using an oxygen carbon cleaner to burn off the carbon deposits in the cylinder by introducing oxygen and igniting the carbon.
- Spot welding sheet metal: The process involves clamping the sheet metal between two dies, applying pressure, and passing an electric current through the dies to melt and fuse the metal at the desired spot.
- Resistance welding two steel bars: This process involves clamping the bars between copper dies, applying pressure, and passing a high-current, low-voltage electrical current through the dies to heat and fuse the bars together.
Conclusion:
“Oxy-Acetylene Welding and Cutting” provides a comprehensive guide to the process, emphasizing the importance of preparation, proper materials, and careful practice. While the manual’s 1914 publication date highlights the rapid industrialization of the time, the principles and practices outlined remain relevant for modern-day welders. The book serves as a valuable resource for understanding the fundamental principles of oxy-acetylene welding, as well as related methods like electric, forge, and thermit welding. Its detailed explanations and illustrations provide a solid foundation for anyone seeking to master the craft.